A crop harvester having an apron whose leading edge is provided with a sickle bar is particularly liable to damage when a plowed-up rock or the like is scooped up by the apron and finds its way into the crop feed. It is necessary that the operator of the harvester pay very careful attention to the sickle bar in order that the apparatus may be stopped and any such picked-up foreign body can be removed before it does any damage to the machine. Should such a rock find its way into the mechanism it can seriously damage the machine, creating considerable expense and undesirable down time.
Devices are known which are provided immediately in back of the sickle bar and which have a pair of downwardly concave parallel members extending parallel to the sickle bar. These members hold stones and other foreign bodies back temporarily so that they are not immediately ingested by the machine. The operator must keep a careful watch in order to see these foreign bodies before they work past the members. Such an arrangement is effective under normal operating conditions; however, if the light is poor, there is considerable dust, or the operator is not paying attention, it is possible for a stone to work its way into the apparatus and damage it.